mason



"(No Model.)

J. H. MASON. TELEPHONE TRANSMITTER.

No. 507,715. Patented Oct. 31, 1893.

UNITED STATES PATE T OFFICE. I

JAMES H. MASON, OF BROOKLY-N, NEW YORK, ASSIGNOR OF NINE-TENTHS TO ALFRED VAN DERWERKEN, OF SAME PLACE.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 507,715, dated October 31, 1893.

Application filed June 6, 1893. Serial No. 476,723. (No model.)

To all whom it may concern.-

Be it known that I, JAMES. H. MASON, of Brooklyn, in the county of Kings and State of New York, have invented a new and useful Improvement in Telephone-Transmitters, of

which the following is a specification.

My invention relates to an. improvement in telephone transmitters with the object in view of rendering the sound transmitted more distinct, increasing the life of the transmitter and providing a transmitter which may be successfully employed either in a direct or in an induced current, as may be desired.

A practical embodiment of my invention is represented in the accompanying drawings, in which- Figure 1 is afront or face view of the transmitter. Fig. 2 is a view in transverse section. Fig. 3 is a plan view of the back plate, and Fig. 4 is a plan view of the front plate.

The part which I have referred to as the back plate consists of a disk A of vulcanized rubber or other suitable material having a coating or film B of aluminum spread or deposited on its face, the said aluminum forming aterminal of an electric circuit through a wire 0. The part which I have referred to as the front plate consists of a disk D of vulcanized rubber or other suitable non-conducting material provided with several holes cl therethrough (in the present instance five) and within a space sufficiently small to be covered by the coating or film B of aluminum when the disks are assembled. A sheet or film E of aluminum foil is constructed to be spread over the face of the disk D covering the holes 61 and forming the other terminal of the electric circuit in which the coating or film B, hereinbefore referred to, forms the one terminal. A clamping ring F of metal or other suitable material is constructed to rest on the front of the film E at or near its outer edge and bolts G extending through the ring and the disks serve to hold the parts assembled.

When the disk D is in assembled adjustment between the films of aluminum, as clearly shown in Fig. 2, the holes d in the disks will serve as pockets for the reception of the conducting medium which completes the electric circuit between the terminals. The said conducting or current-transmitting material with which the holes or pockets cl are filled consists of a granulated or pulverized carbon treated as follows:

The carbon is first boiled for about five minutes in a mixture of paraffiue Wax. The best quality is preferred. It isthen taken out of the wax and placed in a perforated'vessel, preferably a vessel formed of fine wire gauze and baked in a hot oven until the wax ceases to drip from the perforated vessel. This treatment is found by experience to render the carbon unaffected by atmospheric changes, and hence exceedingly durable for the purpose for which it is employed and at the same time its conductivity of the electric current is not materially lessened. Care must be taken, of course, that the bolts G do not establish electric communication between the filmsof aluminum, the necessary insulation of the bolts being provided for in any well known or approved manner. When the disk A is of nonconducting material and the film B does not extend to the bolt holes in the disk, the insulation of the bolts will be completed and this is the arrangement which I prefer. By tightening the nuts on the bolts G, the aluminum foil E is made to bear with greater or lesser force on the carbon fillings, to produce the best effects, and when once adjusted, it requires no further change.

In practice, the vibrations of the film or sheet E are found to be prompt and decisive, producing a transmitted sound of excellent quality, either when the transmitter is in a direct current or is in an induced current and its effectiveness remains unchanged by atmospheric conditions.

The transmitter will operate in any position, either horizontal, upright or inclined, but the upright position is the preferred one.

What I claim is 1. The telephone transmitter, comprising an aluminum film or sheet as one terminal, a second terminal spaced from the aluminum film or sheet and finely subdivided carbon treated with paraffine wax forming an electrical communication between the terminals, substantially as set forth.

2. The telephone transmitter, comprising a the subdivided carbon in hot paraiiine wax,

and subsequently draining the wax out of the carbon under the influence of heat, substan- I5 tially as set forth.

4. The finely sub-divided carbon treated with paraffine Wax, as an electric conductor, substantially as set forth.

JAMES H. MASON.

W'itnesses:

FREDK. HAYNES, F. HOWARD TITLAR. 

